Mark Scheme (Results)

Mark Scheme (Results) Summer 2018

Pearson Edexcel International GCSE In Chemistry (4CH0) Paper 2CR

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Summer 2018 Publications Code 4CH0_2CR_1806_MS All the material in this publication is copyright ? Pearson Education Ltd 2018

General Marking Guidance

All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last. Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions. Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie. There is no ceiling on achievement. All marks on the mark scheme should be used appropriately. All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate's response is not worthy of credit according to the mark scheme. Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited. When examiners are in doubt regarding the application of the mark scheme to a candidate's response, the team leader must be consulted. Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.

Question number

Answer

1 (a)

carbon monoxide

(b)

oxygen

(c)

chlorine

(d)

nitrogen

(e)

chlorine

(f)

nitrogen AND carbon monoxide

Notes ACCEPT CO

Marks 1

ACCEPT O2

1

IGNORE O

ACCEPT Cl2

1

IGNORE Cl

ACCEPT N2

1

IGNORE N

ACCEPT Cl2

1

IGNORE Cl

In either order

1

ACCEPT N2 AND

CO

IGNORE N

Total for Question 1 = 6

Question number

Answer

2 (a) (i) M1 (it/mass) decreases

Notes

Marks 2

M2 (as) carbon dioxide/CO2/gas escapes out of/leaves (the flask)

ALLOW carbon dioxide/CO2/ gas goes into air IGNORE carbon dioxide/CO2 /gas given off/produced /formed on its own

(ii) all (hydrochloric) acid has reacted ACCEPT the acid is used up

1

ALLOW there was not

enough acid to react with

(all the) marble chips

ALLOW acid was the

limiting factor

IGNORE marble chips was

in excess

(iii) mass (of flask and contents) stays ACCEPT stops

1

the same/stops decreasing

bubbling/fizzing/effervescing

IGNORE no more gas

produced/given off

(b) (i) A 1 minute (correct answer as

1

the gradient of the curve is

steeper than at 4, 6 or 8 minutes)

B 4 minutes (incorrect - the

gradient of the curve is less steep

than at 1 minute)

C 6 minutes (incorrect - the

gradient of the curve is less steep

than at 1 minute)

D 8 minutes (incorrect - the

gradient of the curve is less steep

than at 1 minute)

(ii) M1 starts from 0,0 and is steeper

2

than original

curve

M2 levels off before original curve but at same

height

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